Sequence control system



March 25, 1941. c. E. STEWART SEQUENCE CONTROL sys'rmi Filed Sept. .16, 1939 Inventor Clyde E. Stewart,

Hi8 Attorney Patented Mar. 25, 1941 PATENT OFFICE SEQUENCE CONTROL SYSTEM Clyde E. Stewart, Upper Darby, Pa., assignor to General Electric Company, a corporation of New York Application September 16, 1939, Serial No. 295,292

4Claims.

My invention relates to sequence control systems and particularly to a system for controlling the energization of a plurality of electroresponsive devices so that the devices are energized in 5 a predetermined sequence in response to successive operations of a control switch and are deenergized in reverse sequence in response to successive operations of a second control switch,

and one object of my invention is to provide an improved control system of-this type.

My invention will be better understood from the following description when taken in connection with the accompanying drawing the single figure of which diagrammatically illustrates a sequence control system embodying my invention, and its scope will be pointed out in the appended claims.

Referring to the drawing, l, 2 and 3 represent three electroresponsive devices shown as contactors for respectively short circuiting the resistors .R1, R2 and R3 in an electric circuit :01]. The devices i, E'and 3 are arranged to be energized in the order named in response to successive closures of a control switch 3 and to be deenergized in the reverse order in response to successive closures of a second control switch t. The electroresponsive devices I, 2 and 3 have the control relaysia, 2a and 3a associated therewith, respectively. The sequential energization of the devices 8, 2 and 3 in the order named is accomplished by having the energizing circuit of each device include normally closed contacts of the associated control relay and normally open contacts oi the control switch 4 and of the control relay associated with the preceding device in the predetermined sequence and by having each device complete a locking circuit for itself in series with the winding of the associated control relay when the control switch 5 is opened to ill interrupt the original energizing circuit of a device. For example, the energizing circuit of the electroresponsive device 2 includes the normally closed contacts 7; of the associated control relay in and the normally open contacts a of the control switch t and of the control relay la associated with the device i which precedes device 2 in the predetermined sequence. Similarly, the energizing circuit of the electroresponsive device 3 includes the normally closed contacts d of the associated control relay to and the normally open contacts a of the control switch t and of the control relay 2a. The energizing circuit of the electroresponsive device 9 includes the normally closed contacts b of the associated control relay la and only the normally open contacts a oi. the control switch 4 because the device 8 is the first one to be operated in the predetermined sequence.

By closing their respective contacts a, the electroresponsive devices 8, 2 and 3 complete locking circuits for themselves through the windings of the associated control relays. However, each control relay does not become energized until the contacts a of the control switch 4 in the shunt circuit around the control relay winding are opened.

The de-energization of the electroresponsive devices l, 2 and 3 in the reverse order in response to successive, closures of the control switch 5 is eiiected by having each control relay, when it is energized, prepare for itself in shunt to the winding of the associated electroresponsive device a holding circuit which is arranged to be completed by the closing of the control switch 5 if the control relay associated with the succeeding device in the predetermined sequence is de-energized. For example, the control relay la, when energized, prepares through its contacts c and the contacts 12 of relay 2a a shunt circuit around the winding of electroresponsive device 9 so that if the control switch 5 is closed, when both the device i and the control relay to are energized and the control relay 2a is de-energized, the device 6 becomes de-energized because of the shunt circuit around its winding. Similarly, the control relay 2d, when energized, prepares through its contacts c and the contacts I) of control relay 3a a shunt circuit around the winding of electroresponsive device 2 which can be completed by closing the contacts a of the control switch 5. Control relay to, by closing its contacts c, prepares a similar shunt circuit around the winding of the associated electroresponsive device The operation of the control arrangement shown in the drawing is as follows: For the purpose of describing this operation, it will be. assumed that it is desired to energize devices 11 and 2, then de-energize 2, then energize devices 2 and 3 and then de-cnergize devices 3, 2 and i in the order mentioned. This is accomplished by first closing control switch =21 twice, then closing control switch 5 once, then closing control switch l twice and then closing control switch 5 three times. control switch 6 completes an energizing circuit for device i through contact I; of control relay la. When the contacts a of control switch 6 are opened after the first closure thereof, a locking circuit for device I is energized through con- The first closure of the contacts a of tacts a of device l and the winding of the associated control relay la so that this control relay becomes energized. The second closure of the contacts a of the control switch #3 completes an energizing circuit for the electroresponsive device 2 through contacts b of control relay 2a and contacts a of control relay la. When the contact a of control switch ii are opened after the second closure thereof, a holding circuit for device 2 is energized through its contacts a and the winding of control relay 2a so that this control relay becomes energized.

The closing of the contacts a of control switch 5, when only the devices l and 2 are energized, completes a holding circuit for control relay 2a through contacts 0 of relay 2a and contacts b of control relay 8a. so that the winding of device 2 is shunted and this device becomes de-energized. The subsequent opening of the contacts a of the control switch 5 opens the holding circuit of the control relay 2a so that it becomes de-energized.

The next closure and opening of the contacts a of control switch 41 efiects the energization of the electroresponsive device 2 and the subsequent energization of the associated control relay 2a in the manner above described. The next closure of the contacts a of control switch 3, after the control relay 2a is re-energized, completes through contacts a of relay 2a and contacts d of control relay to an energizing circuit for electroresponsive device 3. When the contacts a of control switch 4 are opened after the electroresponsive device 3 is energized, a holding circuit is energized for device 8 through its contacts a and the winding of the associated control relay -3a so that this control relay becomes energized.

The closing of the contacts a of control switch 5, when all of thedevices i, 2 and 8 are energized, completes a holding circuit for the control relay 3a through contacts. 0 of relay 3a so that the winding of electroresponsive device 3 is shunted and becomes de-energized. The subsequent opening of the contacts a of control switch b opens the holding circuit of the control relay 3a so that it becomes de-energized. The next closure and opening of the contacts a of control switch 5 efiects the de-energization of the electroresponsive device 2 and its associated control relay 2a in the manner above described. The next closure of the contacts a of control switch 5 completes a holding circuit for control relay la through contacts 0 of relay la and contacts d of control relay 211 so that the winding of electroresponsive device I is shunted and becomes de-energized. The subsequent opening of the contactsa of control switch 5 opens the holding circuit of the control relay i so that it becomes de-energized and all of the control devices are restored to their normal condition.

,While I have, in accordance with the patent statutes, shown and described my invention as applied to a particular system and as embodying various devices diagrammatically indicated, changes and modifications will be obvious to those skilled in the art, and I therefore aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent 01' the United States is:

1. In combination with a plurality of electroresponsive devices and two control switches. an arrangement for energizing said devices in a predetermined order in response to successive operations of one of said control switches and for deenergizing said devices in the reverse order in response to successive operations of the other control switch including a control relay associated with each of said devices, means for energizing each device except the first to be energized in said predetermined order in response to the operation of said one of said control switches only when the associated control relay is in its normal position and the control relay associated with the preceding device in said predetermined order is in its operated position, means for moving each control relay to its operated position in response to the next restoration of said one of said control switches to its normal position after the associated device has been energized, means for de-energizing each device except the last to be energized in said predetermined order in response to the operation of the other of said control switches only when the associated control relay is in its operated position and the control relay associated with the succeeding device in said predetermined sequence is in its normal position, and means for restoring each control relay to its normal position in response to the next restoration of said other of said control switches to its normal position after the associated device has been de-energized.

2. In combination with a plurality of electroresponsive devices and two control switches, an arrangement for energizing said devices in a predetermined order in response to successive operations of one of said control switches and for de.- energizing said devices in the reverse order in response to successive operations of the other control switch including a normally de-energized control relay associated with each of said devices, means for energizing each device except the first to be energized in said predetermined order in response to the operation of said one of said control switches only when the associated control relay is de-energized and the control relay associated with the preceding device in said predetermined order is energized, means for energizmg each control relay in response to the next restoration of said one of said controlswitches to its normal position after the associated device has been energized, means for de-energizing each device except the-last to be energized in said predetermined order in response to the operation of the other of said control switches only when the associated control relay is energized and the control relay associated with the succeeding device in said predetermined sequence is de-energized, and means for de-energizing each control relay in response to the next restoration of said other'of said control switches to'its normal position. after the associated device has been deenergized.

3. In combination with a plurality of electroresponsive devices and two control switches, an arrangement for energizing said devices in a predetermined order in response to successive operations of oneof said control switches and for deenergizing said devicesin the reverse order in response to successive operations of the other control switch including a normally de-energized control relay associated with each device, an energizing circuit for each device except the first to be energized in said predetermined order including normally closed contacts of the associated control relay and normally open contacts of said one of said control switches'and of the control relay associated with the preceding dehaving in series normally open contacts of said other control switch and normally closed contacts of the control relay associated with the succeed:-

ing device in said predetermined sequence.

4. In combination with a plurality of electroresponsive devices and two control switches, an arrangement for energizing said devices in a predetermined order in response to successive operations of one of said control switches and for deenergizing said devices in the reverse order in response to successive operations of the other control switch including a normally de-energized control relay associated with each device, an energizing circuit for each device except the first to be energized in said predetermined order including normally closed contacts of the associated control relay and normally open'contacts of said one of said control switches and of the control relay associated with the preceding device in said predetermined order. a second energizing circuit for each device in parallel with the other energizing circuit therefor and including in series normally open contacts 01 the device and the winding of the associated control relay, and a shunt circuit around the winding of each device except the last to be energized in said predetermined order and the normally open contacts thereof in said second energizing circuit thereof including normally closed contacts of the control relay associated with the succeeding device in said predetermined sequence and normally open contacts of the associated control relay and of said other control switch.

CLYDE E. STEWART. 

